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FST4/W: Disable envelope shaping at start and end of transmission when environment variable FST4_NOSHAPING=1. Works for fst4sim too.

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Steven Franke 2021-01-18 13:47:54 -06:00 committed by Bill Somerville
parent 5e29c7ebcc
commit 2335575436
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2 changed files with 80 additions and 78 deletions
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2
lib/fst4/fst4sim.f90
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@ -120,7 +120,7 @@ program fst4sim
if(fspread.gt.0.0 .or. delay.ne.0.0) call watterson(c,nwave,NZ,fs,delay,fspread) if(fspread.gt.0.0 .or. delay.ne.0.0) call watterson(c,nwave,NZ,fs,delay,fspread)
if(fspread.lt.0.0) call lorentzian_fading(c,nwave,fs,-fspread) if(fspread.lt.0.0) call lorentzian_fading(c,nwave,fs,-fspread)
c=sig*c c=sig*c
wave=real(c) wave=aimag(c)
if(snrdb.lt.90) then if(snrdb.lt.90) then
do i=1,nmax !Add gaussian noise at specified SNR do i=1,nmax !Add gaussian noise at specified SNR
xnoise=gran() xnoise=gran()

156
lib/fst4/gen_fst4wave.f90
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@ -1,91 +1,93 @@
subroutine gen_fst4wave(itone,nsym,nsps,nwave,fsample,hmod,f0, & subroutine gen_fst4wave(itone,nsym,nsps,nwave,fsample,hmod,f0, &
icmplx,cwave,wave) icmplx,cwave,wave)
parameter(NTAB=65536) use prog_args
real wave(nwave) parameter(NTAB=65536)
complex cwave(nwave),ctab(0:NTAB-1) real wave(nwave)
real, allocatable, save :: pulse(:) complex cwave(nwave),ctab(0:NTAB-1)
real, allocatable :: dphi(:) character(len=1) :: cvalue
integer hmod real, allocatable, save :: pulse(:)
integer itone(nsym) real, allocatable :: dphi(:)
logical first integer hmod
data first/.true./ integer itone(nsym)
data nsps0/-99/ logical first, lshape
save first,twopi,dt,tsym,nsps0,ctab data first/.true./
data nsps0/-99/
data lshape/.true./
save first,twopi,dt,tsym,nsps0,ctab,lshape
if(first) then if(first) then
twopi=8.0*atan(1.0) twopi=8.0*atan(1.0)
do i=0,NTAB-1 do i=0,NTAB-1
phi=i*twopi/NTAB phi=i*twopi/NTAB
ctab(i)=cmplx(cos(phi),sin(phi)) ctab(i)=cmplx(cos(phi),sin(phi))
enddo enddo
endif call get_environment_variable("FST4_NOSHAPING",cvalue,nlen)
if(nlen.eq.1 .and. cvalue.eq."1") lshape=.false.
endif
if(first.or.nsps.ne.nsps0) then if(first.or.nsps.ne.nsps0) then
if(allocated(pulse)) deallocate(pulse) if(allocated(pulse)) deallocate(pulse)
allocate(pulse(1:3*nsps)) allocate(pulse(1:3*nsps))
dt=1.0/fsample dt=1.0/fsample
tsym=nsps/fsample tsym=nsps/fsample
! Compute the smoothed frequency-deviation pulse ! Compute the smoothed frequency-deviation pulse
do i=1,3*nsps do i=1,3*nsps
tt=(i-1.5*nsps)/real(nsps) tt=(i-1.5*nsps)/real(nsps)
pulse(i)=gfsk_pulse(2.0,tt) pulse(i)=gfsk_pulse(2.0,tt)
enddo enddo
first=.false. first=.false.
nsps0=nsps nsps0=nsps
endif endif
! Compute the smoothed frequency waveform. ! Compute the smoothed frequency waveform.
! Length = (nsym+2)*nsps samples, zero-padded ! Length = (nsym+2)*nsps samples, zero-padded
allocate( dphi(0:(nsym+2)*nsps-1) ) allocate( dphi(0:(nsym+2)*nsps-1) )
dphi_peak=twopi*hmod/real(nsps) dphi_peak=twopi*hmod/real(nsps)
dphi=0.0 dphi=0.0
do j=1,nsym do j=1,nsym
ib=(j-1)*nsps ib=(j-1)*nsps
ie=ib+3*nsps-1 ie=ib+3*nsps-1
dphi(ib:ie) = dphi(ib:ie) + dphi_peak*pulse(1:3*nsps)*itone(j) dphi(ib:ie) = dphi(ib:ie) + dphi_peak*pulse(1:3*nsps)*itone(j)
enddo enddo
! Calculate and insert the audio waveform ! Calculate and insert the audio waveform
phi=0.0 phi=0.0
dphi = dphi + twopi*(f0-1.5*hmod/tsym)*dt !Shift frequency up by f0 dphi = dphi + twopi*(f0-1.5*hmod/tsym)*dt !Shift frequency up by f0
if(icmplx.eq.0) wave=0. if(icmplx.eq.0) wave=0.
if(icmplx.eq.1) cwave=0. if(icmplx.eq.1) cwave=0.
k=0 k=0
do j=0,(nsym+2)*nsps-1 do j=nsps,(nsym+1)*nsps-1
k=k+1 k=k+1
i=phi*float(NTAB)/twopi i=phi*float(NTAB)/twopi
i=iand(i,NTAB-1) i=iand(i,NTAB-1)
if(icmplx.eq.0) then if(icmplx.eq.0) then
wave(k)=real(ctab(i)) wave(k)=aimag(ctab(i))
else else
cwave(k)=ctab(i) cwave(k)=ctab(i)
endif endif
phi=phi+dphi(j) phi=phi+dphi(j)
if(phi.gt.twopi) phi=phi-twopi if(phi.gt.twopi) phi=phi-twopi
enddo enddo
! Compute the ramp-up and ramp-down symbols ! Compute the ramp-up and ramp-down symbols
kshift=nsps if(icmplx.eq.0) then
if(icmplx.eq.0) then if(lshape) then
wave(1:nsps)=0.0 wave(1:nsps/4)=wave(1:nsps/4) * &
wave(nsps+1:nsps+nsps/4)=wave(nsps+1:nsps+nsps/4) * & (1.0-cos(twopi*(/(i,i=0,nsps/4-1)/)/real(nsps/2)))/2.0
(1.0-cos(twopi*(/(i,i=0,nsps/4-1)/)/real(nsps/2)))/2.0 k1=(nsym-1)*nsps+3*nsps/4+1
k1=nsym*nsps+3*nsps/4+1 wave(k1:k1+nsps/4)=wave(k1:k1+nsps/4) * &
wave((nsym+1)*nsps+1:)=0.0 (1.0+cos(twopi*(/(i,i=0,nsps/4)/)/real(nsps/2)))/2.0
wave(k1:k1+nsps/4)=wave(k1:k1+nsps/4) * & endif
(1.0+cos(twopi*(/(i,i=0,nsps/4)/)/real(nsps/2)))/2.0 else
wave=cshift(wave,kshift) if(lshape) then
else cwave(1:nsps/4)=cwave(1:nsps/4) * &
cwave(1:nsps)=0.0 (1.0-cos(twopi*(/(i,i=0,nsps/4-1)/)/real(nsps/2)))/2.0
cwave(nsps+1:nsps+nsps/4)=cwave(nsps+1:nsps+nsps/4) * & k1=(nsym-1)*nsps+3*nsps/4+1
(1.0-cos(twopi*(/(i,i=0,nsps/4-1)/)/real(nsps/2)))/2.0 cwave(k1:k1+nsps/4)=cwave(k1:k1+nsps/4) * &
k1=nsym*nsps+3*nsps/4+1 (1.0+cos(twopi*(/(i,i=0,nsps/4)/)/real(nsps/2)))/2.0
cwave((nsym+1)*nsps+1:)=0.0 endif
cwave(k1:k1+nsps/4)=cwave(k1:k1+nsps/4) * & endif
(1.0+cos(twopi*(/(i,i=0,nsps/4)/)/real(nsps/2)))/2.0
cwave=cshift(cwave,kshift)
endif
return return
end subroutine gen_fst4wave end subroutine gen_fst4wave